Is 1904 Code of Practice for Design and Construction of Foun

1s : 1904- 1986 Indian Standard ( Reaffirmed 1995 ) CODE OF PRACTICE FOR DESIGN AND CONSTRUCTION OF FOUNDATIONS IN SOILS : GENERAL REQUIREMENTS ( Third Revision) First Reprint JULY 1989 UDC 624’15’04 : 006’76 0 Copyright 1987 ” BUREAU &¶ANAK OF BHAVAN, 9 INDIAN BAHADUR NEW DELHI 110002 STANDARDS SHAH ZAFAR MARG Gr 6 November 1987 IS : 1904 - 1986 Indian Standard CODE OF PRACTICE FOR DESIGN AND CONSTRUCTION OF FOUNDATIONS IN SOILS :, GENERAL REQIJIREMENTS Foundation Chai~ilrnn MAJ-Gtld OMIIBIR SINGH ,\iervbers Engineering Sectional Commitree, BDC 43 GOL K. P. ANAND ( Airrrnare to Maj-Gen Ombir Singh ) Ministry of Railways ( R.DSO ) ADUITIONALDIKECTQR GE ) ( ADDITIONALDIRECTOR( S ) ( Alternate ) Ministry of Communication Smr K. K. AGC~.AHWAL I~aboratorics, Research SHKl H. rthJlAH Engineering A. P. Hyderabad Stm! ARJUN RIJHSISGHANI Cement Corporation of India, New Delhi SHRI 0. S. SRIVASTAVA .4/ter/;ate ) ( Central Building Research Institute ( CSIR ), DH IL K. BHANDARI Roorkee SFII~ICHA~DRA PI<AKAS!I Aito~nnte ) ( SHKI MAH\BII<UIDASAKIA Ferro-Concrete Consultants Pvt Ltd, Indore SHKI ASHOK BID.~s;\KI.\ Alternate ) ( SmI S. P. CHZKKABARTI Ministry of Transport ( Roads Wing ) SII~CI K. DA.ITA ( Alternate ) P. Sty A. K. CH~TTERJEH Gammon India Ltd, Bombay SHIP A. C. ROY ( Akmfe ) CHIEF E~G~~EEII Calcutta Port TrusL Calcutta SHRI S. GUH\ ( Alternate ) Simplex Concrete Piles (I) P\t Ltd, b7alcutta SHRI R. K. DAS GUP~A SHRI EL GUHA BISWAS ( Alternate ) SHKI A. G. DASTI~AR In personal capacity ( 5 Hungerford Court, 121 Hungerford Street, Calcutta ) ( Contiwed (c Copyright I987 OF INDIAN STANDARDS on page 2 ) BUREAU This Gublication is protected under the Indian: Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act. D. R.1986 ( Cotttintcdfroin Members SHR!V. V. MXTRA( Alternate j G. KULKARNI SHRJ S. MAThWit Joiut Director ( Civ Engg j. JAOANNATH SHRI A. Guindy. Bombay Construction Private SHRI A. New Delhi JOJNT DJRXTOR ( D~SJGN ) SHRI SUNJLBERY( Alternate j Indian Institute of Technology. New SKRI A. S. IYWOAR ( Abemate j SHRJA. H. Jain & Associates. New Delhi Mckenzies Ltd. PANTHAKY SHRI V. GHOSHAL University of Roorkee. Durgapur SHRIN. Roorkee DR GOPALRANJAN Steel Authority of India Ltd. Dastur & Company Pvt Ltd. M. R. MURT~ &al B. Bombay capacity (E104A Simia House. RAO DR A. New Delhi SHRI ASHOKK. New Delhi Central Public Works Department. S. Bombay College of Engineering. MAUGB ( Alternate) SHRTM. N.\RJAIN ( Alternate ) National Buildings Organization. P. MUNSJ SHRJ M. DFSHPANDE DIRBCTOR( CSMRS) page 1 j Representbtg Pressure Piling Co ( I ? Pvt Ltd. J. VARADARAJAN DR R. Bombay. Bombay Cemindia Company Ltd. KAXXRAJ AIterMIe j ( SHR1G. Cent$lbotl & Mater& Research Station. M. Bombay SHRI A. B. KATTI M. N. JAIN SHRI VIJAYKUM. New Delhi Director General. JANOL~( Alternate j Stup Consultants Limited. K. S. MATHUR SHRI S. K. SUPSKJNTZNDJFZG ENGINEER ( DEsroNs ) HXWXTYV~ ENUINEER DESJQNS ( V ( Alternate ) DR A. MUKHERJEE S~RJ T. K. D~VANJ~ CHIEFR&SEARCH OPP:Cfx ( CSMRS ) ( Afternote j Asia Foundations and Limited. Calcutta ‘SIIRJ S. V. Madras Nagadi Consultants Private Limited. C. ROY ( Alternate j SHRJA. K. RAMAN. R. K~TKAR ( Alternate) Dr V. New Delhi Nepean Sea Rwd. New Delhi Hindustan Coostruction Co Ltd. MATHUR SHRI V. 111 personal Central Warehousing Corporation. Bombay DR R. Bombay ) Indian Geotechnical Society. SARGWAN SZZRS B~MMINATHAN ( Alternate S. 63 ( Ex-oficio Member ] Director ( Civ Engg j Secretury SRRI K. Engineers India Limited. PUNJA SERI D.IS : 1904. New Delhi j j Indian Institute of Technology. BIS ( Cwstinued on page’ 22 ) 2 . In order that these general requirements are not repeated in each of such Indian Standards. which is also being revised simultaneously. foundation and super-structure should be studied as a whole. the supporting ground.IS:1904-1986 Indian Standard CODE OF PRACTICE FOR . therefore. 0. DESIGN AND CONSTRUCTION OF FOUNDATIONS IN SOILS : GENERAL REQUIREMENTS ( Third Revision) 0.3 The design of the foundation. types of foundations (shallow. FOREWORD Standard ( Third Revision ) was adopted by the Indian Standards Institution on 31 October 1986. Opportunity has also been taken to transfer the general requirements covered in IS : 1080-1980*. which covered requirement for shallow foundations. In order to obtain maximum economy. This Indian Standard was first published in 1961 and revised in 1966 and 1978. this basic Indian Standard covering such general requirements has been formulated.2 Series of indian Standards on design and construction of various. 0.1 This Indian 3 . after the draft finalized by the Foundation Engineering Sectional Committee had been approved by the Civii Engineering Division Council. The design of a foundation involves both geotechnical aspects of supporting ground and the structural aspects of the foundation materials. It was. The aim is to proportion the foundation ( plan dimensions ) in such a way that net loading intensity of pressure coming on the soil does not *Code of praet& for design and construction of simple spread foundations (firsr revision ). 0. decided to revise this standard so as to cover the general requirements for design and construction not only for shallow foundation-but also for all types of foundations. so that it covers only the specific requirements applicable to design and construction of shallow foundations. Many of the requirements for designing of such foundatidns are common for all types of foundations. During the past seven years. deep and special types) have been formmated covering their specific requirements. super-structure and the characteristics of the ground are inter-related. new Indian Standards covering design and construction of various types of foundations have been formulated. shall be rounded off in accordance with The number of significant places retained in the rounded IS : 2-1960*. IS : 2809-19721 shall apply. TYPES OF FOUNDATIONS the definition of terms given in for all types in which 3.1 For the purpose of this standard. Kode of practice for design and construction of ring foundation. observed or calculated. TERMINOLOGY 2. the final value.1 The various b) Strip types of shallow foundations are as under: a) Spread ofpad c) Raft foundation pee IS : 1080-1986:. generally in the form of piles.1 Shallow Foundations . SCOPE 1. 2.2 Deep Foundations . $Code of practice for design and construction of raft foundations : Part 1 Design ( second revision ).IS : 1904. tGlossary of terms and symbols relating to soil engineering ( first &vision ).4 For the purpose of deciding whether a particular requirement of this standard is complied with.These cover such types of foundations load transference is primarily through shear resista’nce of the bearing strata ( the fractional resistance of soil above bearing strata is not taken into consideration ) and are laid normally to depth of 3 m.1986 exceed the safe bearing capacity and that structural design which involves the determination of the thickness of elements so that maximum stress in concrete ( plain or reinforced ) and masonry is within permissible limits. IS : 11089-19841~ and IS : 94. 0. SCode of practice for design and construction of shallow foundations in soils ( other than raft. ring and shell ) ( second revision ). 3.56- d) Ring and shell foundation --see 19807. deep and special types ). expressing the result of a test or analysis. diaphragm walls. See IS : 2950 ( Part 1 )-19815. Wade of practice for design and construction shell foundations. used separately or in combination to transmit *Rules for rounding off numerical values ( revised ). 4 of conical and hyperboloidal typea of . 3.1.1 This standard covers the general structural requirements of foundations ( shallow. See IS : 1080-1\986$.This is a foundation caissons. . off value should be the same as that of the specified value in this standard. 3. 1. c) Diaphragm walls .Foundations for certain structures and/or machineries require speciai design and detailing procedure taking into consideration the impact and vibration characteristics of the load and the soil properties under dynamic conditions and may have combination of foundation structure. ttCode of practice for design and construction of machine foundations : Part 2 Foundations for impact type machine ( Hammer foundations ) ( first revision ).2.1986 the loads to a deeper load bearing strata ahen.See IS : 2911 ( Part l/Set l)-1979*.See IS : 2911 ( Part 2 )-1980t. $Code of practice for design and construction of port and harbour structures : Part 1 Concrete monoliths.See IS : 9527 ( Part 1 )-1981s.3. Urzder-reamed pi/p . **Code of practice for design and construction of machine foundations : Part 1 Foundation for reciprocating type machines ( second revision ) . The transference of load by a deep foundation may be through friction. Board cast in-situ .1s: 1904.See JS : 2911 ( Part l/Set 4 )-1984*. b) Caissons .See IS : 2911 ( Part l/Set 2 )-1979*. : Part 2 Timber $Code of practice for design and construction of pile foundations : Part 3 Underreamed piles ( first revision ). *Code of practice for design and construction of pile foundations : Part 1 Concrete piles ( Sections 1 to 4 ) ( firsr revision ).1 The various types of such foundations are as under: a) Machine foundations 1) Reciprocating type See IS :‘2974 ( Part 1 )-1982**. no adequate bearing strata exists at shallow depths. 3. d) Well foundationI.See IS : 2911 ( Part l/Set 3 )-1979*. Timber .See IS : 2911 ( Part 3 )-1980$. 3. tCode of practice for design and construction of pile foundations piles ( first revision ). ‘-A detail code on this subject is formulated by IRC. 3. end-bearing or a combination of both. IiCode of practice for design and construction of diaphragm walls. 5 . Board precast .See IS : 9556-198011.3 Foundations for Special Structure . 2) Impact type - See IS : 2974 ( Part 2 )-1980tt.1 The various types of deep foundations are as under: a) Pile Foundations 1) 2) 3) 4) 5) 6) Driven cast in-situ . Driven precast . e) Combirzedfoundations - Two or mnre types of above foundations. to the 5. The exploration of the site for an important structure requires the exploration and sampling of all strata likely to be significantly affected by the structural load. As a preliminary.1 The natural geological deposits over. 6 .1 The investigation of the site is an essential prerequisite to theconstruc.IS: 1904-1986 3) Rotary type ( medium and high frequency ) (Part 3 )-1975*. old drains. or tCode of practice for design and construction of machine foundations : Part 4 Foundations for rotary type machines of low frequency ( first revision ). microwave and TV tower foundations. particular attention shall be paid to the ground water level. tion of all civil engineering works with a view to assess the general suitability of the site for the proposed new works and to enable in preparing an adequate and economic design. wells. aCode of practice for subsurface investigation for foundations ( first revision). 5) Impact type ( other than hammer j . The extent of this exploration will depend on the site and structure. etc.See IS : 2974 ( Part 4 )-1975t. l/Code of practice for design and construction of radar antenna. underground water courses.2 The investigation of the site should be carried out in accordance with the principles set in IS : 1892-19797. In any case. it is usually judicious to collect information relating to the site prior to commencing its exploration. 5. $Code of practice for design and construction of machine foundations : Part 5 Foundations for impact type machines other than hammers ( first revision ). 4. b) Tower foundations 1) Transmission line towers and poles - See IS : 4091-19795. §Code of practice for design and construction of foundations for transmission line towers and poles ( first revision). it is necessary to assess the changes that may occur during or after the construction of the structure due to the choice of materials or methods of construction which may adversely affect safety of structure or after its performance or utility. TV tower See IS : 11233- 2) Radar antenna. pits. See IS : 2974 4) Rotary type lowfrequency . SITE INVESTIGATION 5. base rock extending surface level of the earth should be examined.‘. and presence of excessive sulphates or Other *Code of ractice for design and construction of machine foundations : PM 3 Foundations F rotary type machines ( medium and high frequency ) ( firsf revision ).SeeIS : 2974 ( Part 5 )19%7$. GROUND microwave and 4. 198511. old foundation. In particular. These conditions are simulated. therefore. 7 . sequence and dip of the strata. depends on the type of soil. the angle of slope. indicate the creep of the surface layers. 5. tilted fence posts. The magnitude of the movement and its distribution pver the area of the workings and their vicinity can be roughly estimated. by extraneous agencies like trees. if they are cut down. if necessary. furnaces. services and refrigeration installations. These include mining subsidence. These factors shall be observed in detail during site investigation and taken into account in the layout and design of the proposed works. Swelling may occur. Instability may develop even after a long period of apparent stability. ground water regime and climatic conditions. kilns. These factors shall be studied carefully before designing any foundations. Expert advice from appropriate mining authority should be sought.3 Some clayey soils are susceptible to shrinkage and cracking in dry and hot weather. Uneven surface of a slope on virgin ground. Long continuous buildings should be avoided and large building should be divided into independent sections of suitable size. expert advice regarding the geological and hydrologicai characteristics of the site shall be sought. Where future subsidence is likely. and swelling in wet weather.3. thickness.3. etc. be avoided. each with its own foundations. 5. underground cables.IS:l!M4-1986 injurious compound in the ground water and soil. On sloping ground on clay soils there is always a tendency for the upper layers of soil to move downhill. 5. unstable slopes and creep on clay slopes. however. NO trees which grow to a large size shall be planted within 8 m of foundations of buildings. the extent. excavations or sloping ground near foundations may increase the possibility of shear failure in the ground supporting the foundations. sometimes.2 Cuttings.3. where necessary. Shrinkage of clay soils may be increased by the drying effect produced by nearby trees and shrubs. care should be taken to design the superstructure and foundation sufficiently strong or sufficiently flexible to cater for probable ground movements. to ascertain the type consistency. However. Areas subject to land slip and unstable slopes shall.3 Mass movements of the ground are liable to occur from causesindependent of the loads imposed by the structure. particularly in stiff. fissured and over consolidated clay soil.1 Mining subsidence is liable to occur in mining areas. boiler installations. tilted boundary walls. 5. curved tree trunks. land slips. The site should also be explored in detail. 3. cutting through existing land drains.4 New constructions may interfere with drainage regime of the ground and affect the stability of existing structure. consideraticn should be given for diverting into the ground-drainage system. land drainage requires special consideration for diverting the If excavation involves natural flow of water away from the foundations. the water-table surface in order to indicate the directions of the natural drainagd and to obtain the basis of the design of intercepting drains to prevent the influx of ground water into the site from higher ground. It is generally determined by measuring the water level in the borehole after a suitable time lapse for which a period of 14 hours or more be used as the case may be. corrosive action may arise from industrial wastes that have been dumped on the site. give an erroneous impression of the true ground water level. the water levels in boreholes or observation wells may take a considerable time to reach equilibrium with ground water Spot readings of Vater level in boreholes may. 8 . lapse of sometime is ustially suffizient.1S : 1904. unless the hole has been sealed with drilling mud. Adequate precautions On the uphill side of a building on a should be taken to protect these. Where deep excavation is required.1986 5. On sites liable to be water iogged in wet weather. sloping site. therefore. *code of practice for plain and reinforced concrete ( rhird revision ). Chemical analysis of samples of ground water or soil ( or sometimes both ) should be done to assess the necessity of speciai precautions. The following are settle of suggested methods: a) Dense cement concerete M20 mix or richer may be used to reduce permeability and increase resistance tc attack from sulphates ( see I§ : 456-1978” ). it is desirrable to determine the contour of. In industrial areas. such as sand and gravels. especially thin members or buried metals are subjected to deterioration and corrosion. In case of soils with low permeability. particular1.ring strata should be determined with particular care and the water pressure in each should be observed so that necessary precautions may be taken during excavation. %3. In soils with high permeability.6 In certain localities where considerable quantities of soluble salts are contained in ground water and soil.y on cast iron.§ Increase in moisture extent results in substantial loss of bearing capacity in case of certain types of soils which may lead to differential settiements.3. In these cases it nay be necessary to resort ?o indirect means to estab!ish the approximate location of the water table. The seasonal variation in the level of the water table is of importance in some cases. Certain soils have a corrosive action on metals. portland cement concrete. 5. due to either chemical or bacteriological agency. the location of water bea. NOTE .The soluble salts are usually sulphates of calcium.2 percent SO. and due to trees and shrubs are likely to cause appreciable movements. This reaction is accompanied by considerable expansion which leads to the deterioration and cracking of the concrete. METHODS OF SITE EXPLORATION methods of site explorations are 6. 6. by weight of clay in air-dry condition.1 The depth to which foundations should be carried depends upon the following principal factors: The securing of adequate allowable bearing capacity. c) Special cements like high alumina cement. Water containing these salts gets into the concrete and reacts with the set cement or hydraulic lime.1 The most common and satisfactory given below: a) Trial pits. may be used. super sulphated cement. -____- below the zone in which trouble *Specification for bitumen mastic for tanking and damptproofing. which should be determined by proper analysis. 9 . penetration below the zone where shriakage and swelling due to seasonal weather changes. tCode of practice for subsurface investigation for foundation (first revision 1. The amount of soluble sulphates may be considered excessive from the point of attack on concrete if it is more than 30 parts of SO. per 100 000 parts of subsoil water or in the case of clays if more than 0. penetration may b9 expected from frost. which are sulphate resistant. DEPTH OF FOUNDATION 7. magncaiumand sodium. e) A thick layer of cement concrete (with sulphate resistant cement ) and coated with bitumen be laid before laying of foundation concrete to prevent infiltration of water from sulphate bearing soil. In fine sands and silts. The details of these methods are given in IS : 1892-1979f. 7. b) Boring. In the case of clayey soils. and c) Headings. d) A thick coating of bitumen may be given over the exposed surfaces of foundation below the water table to prevent infiltration of water into the foundation ( see IS : 5871-1970* ).b) Portland pozzolana cement may be used to control and reduce the activities of the sulphates. 7. water course.1Where footings are adjacent to sloping ground or where the bottoms of the footings of a structure are at different levels or at levels different from those . ditch. if necessary.4 A foundation in any type of soil shall be below the zone significantly weakened by root holes or cavities produced by burrowing animals or works. Adequate load counteraction swelling pressures also provide satisfactory foundations. 7.of the footings of adjoining structures. pond. FOUNDATION AT DIFFERENT LEVELS .rs:l!xM-1986 a) The maximum depth of scour. are seasonally affected by drying.5 Clay soils. On rock or such other weather resisting natural ground. wherever relevant. shrinkage and cracking in dry and hot weather. the sloping surface shall not intersect a frustum of bearing material IO . It is necessary in these soils. the surface shall be cleaned and. e) Other factors such as ground movements and heat transmitted from the building to the supporting ground may be important. 7. In suchcases. either to place the foundation bearing at such a depth where the effects of seasonal changes are not important or to make the foundation capable of eliminating the undesirable effects due to relative movement by providing flexible type of construction or rigid foundations.3 Where there is excavation. The depth shall also be enough to prevent the rainwater scouring below the footings. filled up ground or similar condition adjoining or adjacent to the subsoil on which the structure is to be erected and which is likely to impair the stability of structure. like black cotton soils. stepped or otherwise prepared so as to provide a suitable bearing and thus prevent slipping or other unwanted movements. or retaining walls or similar works shall be constructed for the purpose of shielding from their effects.2 All foundations shall extend to a depth of at least 50 cm below natural ground level. removal of the top soil may be all that is required. 8. 8. 7. the depth of the footings shall be such that the difference in footing elevations shall be subject to the following limitations: a) When the ground surface slopes downward adjacent to a footing. and by swelling in the following wet weather to a depth which will vary according to the nature of the clay and the climatic condition of the region. either the foundation of such structure shall IX carried down to a depth beyond the detrimental infiuence of such conditions. should also be considered and the foundation should be Iocatqd sufficiently below this depth. Leakage from water mains and underground sewers may also result in large volume changes. The shrinkage of clay will be increased by drying effect produced by fast growing and water seeking trees. kilns. it is desirable that there shall be a distance of at least g m between such trees. installations and other artificial sources of heat may . dry weather a deficiency of water develops near the ground surface and in clay soils.1 During periods of hot. Railer furnaces. this is associated with a decrease of volume or ground shrinkage and the development of cracks. special care must be taken to prevent such leakages. 2 ). underground cables and refrigeration installations. the drying out can be to a substantial depth. Therefore.IS:1904-1986 under the footing having sides which make an angle of 30” with the horizontal for soil and horizontal distance from the lower edge of the footing to the sloping surface shall be at least 60 cm for rock and 90 cm for soil ( see Fig.9. 9. 1 ). clay soils swell and the cracks lend to close. Special precautions either in the form of insulation or otherwise should be taken. EFFECT OF MASS MOVEMENTS OF GROUND IN UNSTAB]LE ARRAS 10. In case of footing of clayey soils a line drawn between the lower adjacent edge of the upper footing and< the upper adjacent edge of lower footing shall not have a steeper slope than one vertical to two horizontal ( see Fig.1 shall not apply under the following 8. b> In the case of footings in granular soil. 10. given in 8.2 The requirement conditions: aj Where adequate provision is made for the lateral support ( such as with retaining walls ) of the material supporting the higher footing.0 In certain areas mass movements of the ground are liable to occur from causes independent of the loads applied by the foundations of 11 . the water deficiency developed in the previous dry periods may be partially replenished and a subsurface zone or zones deficient in water may persist for many years. b) When the factor of safety of the foundation soil against shearing is not less than four. The range of intluence depends on size and number of trees and it increases during dry periods.also cause increased volume changes of clay by drying out the ground beneath them. 2 ). In periods of wet weather. EFFECT OF SEASONAL WEATHER CHANGES . a line drawn between the 4 lower adjacent edges of adjacent footings shall not have a steeper slope than one vertical to two horizontal ( see Fig. In general. 2 OF JOINING LINE NOT STEEPER 1HAN ONE VERTICAL 10 TWO HORIZONTAL LOWER F 00TlN~ &WING IN GRANULARSort OR CLAYEY SOIL 12 . 1 FELTINGIN SLOPING GROUND L SLOPE FIG.THESE SURFACES SHOULD NOT INfERSECr FIG. 2. In this connection. be directed to make the foundations and structures sufficiently rigid and strong to withstand the probable worst loading condition. excavations or sloping ground near and below foundation level may increase the possibility of shear failure of the soil.the slopes shall be stabilized.1 The construction of structures on slopes which are suspected being unstable and are subject to landslip shall be avoided. 10.3 Where there may be creep of the surface layer of the soil.1. they shall be lapped at the bearing and stepped.2. whichever is greater. and creep on clay slopes.7 Cuttings and excavations adjoining foundations reduce stability and increase the likelihood of differential settlement.2 On Joping ground on clay soils. unless special precautions are taken. 10.2 Landslip Areas 10.5 Cuttings. the uneven surface of the slope on a virgin ground bill indicate that the area is subject to if used for foundation. the structure shall be kept well away from the top of the slopes. In case of doubt. tude of the movement and its distribution over the area are likely to be uncertain and attention shall. the angle of slope.2. spread foundations At ail changes of levels. 10.2.3. mining subsidence.2. as to the suitabmty of the natural slopes or cuttings. reference should also be made to 5. climatic conditions. necessitate special design consideration. etc.IS:1904 These include structures. or. will obviously small iand slips and. the latter shall be made strong enough to resist any unbalanced thrust. steps for a distance at least equal to the thickness of the foundation or The steps sha!l not be of twice the height of the step. depending on lype of soil. 13 . landslips on unstable -1986 slopes 10.2.1 Mining Subsidence . therefore. In some cases. subsidence of the ground The magnibeneath a building or any other structure is liable to occur.2.6 If the probable failure surface intersects a retaining wall or other revetment. Their effect should be investigated not only when they exist but also when there is possibility that they are made subsequently. shall be on a horizontal 10.In mining areas. therefore. The foundation shall be well beyond the zone of such shear failure. protection against creep may be obtained by following special design considerations. of 10. there is always a tendency for the upper layers of soil to move downhill. 10.4 On sloping sites. 10. greater height than the thickness of the foundation. The ground itself. These should be taken into account. If the slope of the ground is large. The softer layers may undergo marked changes in properties if the loading on them is increased or decreased by the proposed construction or affected by related changes in ground water conditions.1 Loads on a foundation are those forces imparted by thestructure. 15. land drainage also requires special consideration. particularly if of clay. 11. 13. if they dip towards a cutting or basement.1 Strata of varying thickness. particularly on the uphill side of a structure to divert the natural flow of water away from the foundations.2. 14 .1 In the case of inclined FOR FOUNDATIONS ON INCLINED STRATA strata.8 Where a structure is to be placed on sloping ground. While the adoption of such provision shall help minimizing damage to adjacent foundation.1 Some soils and rocks have layers of harder material between thin layers of softer material. When there is large change of thickness of soft strata. it is supporting. the stability of foundation may be affected. STRATA OF VARYING THICENESS 12. ensure detection of significant variations in strata thickness. therefore. These aspects should be carefully investigated. PRECAUTIONS 11. may be subject to creep or other forms of instability. the greater the damage is likely to be. the overall stability of the slope and substructure may be affected. Where necessary.1 The deeper the new foundation and the nearer to the existing it is located. which may not be detected unless thorough investigation is carried out. Site investigations should. 14. may increase differential settlement. 12. an analysis of bearing capacity and settlement shall be carried out to have an appreciation of the effect on the adjacent existing foundation. additional complications are introduced. it may be necessary to carry foundation below the possible slip planes. even at appreciable depth. which may be enhanced if the strata dip in the same direction as the ground surface.Is: 1904-1986 10. LOADS ON FOUNDATIONS 15. The minimum horizontal spacing between existing and new footings shall be equal to the width of the wider one. SPACING BETWEEN EXISTING AND NEW FOUNDATION 14. LAYERS OF SOFTER MATERIAL 13. in any of the form (i) vertical either upwards or downwards. calculations should be made of the estimated settlement from different thicknesses of strata and the structure should be designed accordingly. Due to its transitory nature.IS:l!304-1986 (ii) horizontal or lateral. 15.7 Where wind or seismic load is more than 25 percent of that due to dead and live loads.1 Uniform Settlement .ndations. 15. When seismic forces are considered.4 Dead load also includes the weight of column/wall.1. dead + live -. SETTLEMENT 16. 16. The following loads 151. 15. 15.1 Pemzanent Load . foundations may be so proportioned that the pressure due to combination of load ( that is. it may be neglected in design and first combination of load shall be compared with the safe bearing load to satisfy allowable bearing pressure. In non-cohesive soils.‘-wind load ) does not exceed the safe bearing capacity by more than 25 percent. In *Code of practice for strucfural safety of buildings Imposed loads ( second rev&&w : Loading standards : Pati 2 tcriteria for earthquake resistant design of structures (fourrh revision ).1.1.1. footings. 15 .3 Foundations shall be proportioned of loads: for the following combination a) Dead load + live load. analysis for liquefaction and settlement under earthquake shall also be made. 15.16 Where wind or seismic load is less than 25 percent of that due to dead and live loads.This is a momentary or sudden load imparted to a structure due to wind or seismic vibrations.This is the actual service load/sustained load consisting of dead loads and live loads of a structure which give rise to stresses and deformations in the soil below foundation causing its settlement. and (iii) moment or couple. the overlying fill but excludes the weight of the drsplaced .1. and b) Dead load + live load + wind load or seismic load. shall be considered for design of foundations.2 Transient Load . the stresses in the soil below the foundation carried by such loads are allowed certain percentage increase over the allowable safe values. depend on the rigidity of substructure and compressibility of the underlying strata. z.The magnitude of the settlement that should occur. 15. the safe bearing capacity shall be increased as specified in IS : 1893-1984t.5 Live loads from the floors above as specified in IS : 875 ( Part 2 )1987* shall be taken in proportioning and designing the foundations. when foundation loads are applied to the ground. the engineer-in-charge should be well familiar with all causes of settlement. for example. and density of the soil medium ( pockets of sand in clay. need be made for this slow consolidation settlement. thickness. surface erosion. Prolonged lowering of the water table in fine grained soils may introduce settlements because of the extrusion of water from the voids. and g) The effects of vegetation soils.The foundations of different elements of a structure may have unequal settlements and the difference between such settlements will cause differential settlement. Foundations may settle due to some combination of the following reasons: a) Elastic soil. in a period of time. peat. Some of the causes for differential settlements are as follows: 4 Geologic and physical non-uniformity or anomalies in type. leading to shrinking subsidence and swelling of clay 16. Non-uniform pressure -W to non-uniform due foundations. distribution from foundation to the soil loading and incomplete loading of the site. For the safety of foundations. an admixture of organic matter. such as adjacent excavation. Pumping water or draining water by wells or pipes from granular soils without adequate filter material as protection may. settlement may continue almost activities.2 Differential Settlements -. and the underlying b) Consolidation including 4 Ground Wufer Lowering-specially repeated lowering and raising of water level in loose granular soils tend to compact the soil and cause settlement of the foundations. carry a sufficient amount of fine particles away from the soil and cause settlement. In sand and gravels.IS:1904-1986 silts and clays the settlement may continue for a long period after the construction of structure. mining underground erosion by streams or floods. that is. lenses in soil ). compression of the foundation secondary material compression. wedge like soil strata. and d) Seasonal swelling and shrinkage e) Ground movement on earth slopes. f) Other causes. Qructure. the settlement is likely to be complete to a great extent by the end of the construction In strata of organic soils. etc. mud. Cl Varying water regime at the construction 16 . Due allowance shall. slow creep or land slides. of expansive clays. therefore. clay lenses in sand. indefiniteiy. Generally. softening and drying of soils.1986 d) Over stressing of soil at adjacent next to light ones. 16. This may be done by the following procedure: a) Determine the required bearing area for a column having the ln the conventional method largest live load to dead load ratio. the settlements shall be estimated corresDead load and all fixed equipments are ponding to permanent loads.1 For foundations resting on coarse grained soils. g) Non-uniform development of extrusion settlements. shall IS : 8009 (Part be not more 1) d) For calculation of settlement -1976 * may be referred. it appears reasonable to reduce the differential settlement due to live load variation by maintaining equal pressure for all foundations under the service load. the settlements shall be estimated corresponding to the load mentioned in 15. 16. the area (A) is given by: A = -Dead load + live load . and h) Non-uniform structural disruptions or disturbance of soil due to freezing and thawing. built in soil from adjoining f) Unequal expansion of the soil due to excavation for footings.1.2 For fine grained soils. since in such type of soils. 16. Bearing area = SerViCe load iqd of foundations.3.3 Criteria for Settlement Analysis for Shallow Foundation 16. 17 foundations .3. The engineer shall use his judgement in each project work to determine what loads are permanent and what are temporary. considered as permanent.3 The total settlement permissible.IS : 1904 . that is. Allowable bearing capacity b) Compute for this same column qd = the design bearing value service load A c) Determine the area for all other COlUmnS by the use of qd. one half of the design live load may be taken as being permanent. of design. of the foundations than *Code of practice for calculation of foundatioos : Part 1 Shallow subjected to symmetrical static vertical loads.3(b). settlements occur within a very short period of loading.3. e) Overlap of stress distribution site by heavy structures structures. swelling. Therefore. tCode of practice fo: determination of bearing capacity cf shallow {first revirron ). The tactor of safety of other types of foundation is covered in relevant Indian Standard ( see 3).5 Differential settlement and/or tilt ( angular distortion ) of the structures shall not be more than the permissible values.4 Settlement Analysis for Deep Foundation 16. When dead load. and the factors of safety shall conform to the following requirements. 17. BEARING CAPACITY l8. Tilt shall be calculated by dividing the differential settlement by the distance between points of related maximum and minimum settlement.4. the factor of safety shall be not less than 2. 6403-1981t. The settlement shall be calculated according to IS : 8009 (Part 2)-1980*. the factor of safety shall be not less than l-75. live load and earth pressure only are considered.1. and tilt ( angular distortion ) have been specified in the relevant Indian Standard (see 3).The factor of safety against sliding of structures which resist lateral forces (such as retaining walls) shall be not less than 1a5 when dead load. Nore . 1 against 13. live load and earth pressures only are considered.2 Overturning .1 The stability of the foundation against sliding and overturning shall be checked. safety against sliding may be improved by providing anchor type cut-off walls or piles to fake the excess load over that resisted by friction or an inclined underside of the base. live load and earth pressures are considered together with wind load or seismic forces.3. live load and earth pressures are considered together with wind load or seismic forces.For structuresfounded on soils with low frictional coefficient ( that is. 16. 17 STABILITY AGAINST OVERTURNING AND SLIDING 17. .1.5 when dead load. The permissible value of total sett!ement. differential settlement.4 The permissible value of settlement for different types of structures are given in Table 1. slippery material ). 18.IS:1904-1986 16.1 Sliding .3.1 The sale bearing capacity for shallow foundation shall be calcuiated in accordance with IS . 16.The factor of safety for shallow foundation overturning shall be not less than 1. . When dead load. The diflerential settlement shall be obtained by taking the difference maximum and minimum settlement. The method of computation of sa?c bearing capacity for other types of foundations has been specified in the foundations foundations *code Of practice for calculation of foundations: Part 2 Deep subjected to symmetrical static vertical loading. UO2L l/u)0 75 g02L l/500 75 oW25L l/400 12s 09033L l/300 *02L l/So00 60 Wo2L l/So00 tj .TABLE 1 PERMISSIBLE DIFPERENTUL SRTTLEMENTS AND TILT (ANGULAR DISTORTION 1 FOR SHALLOW FOUNDATION IN SOfLS (Clarise 16.4L l/25@ 1 2) L/H .4 j &XATBD SI mured FOUNDATION8 * RAFT FOUNDATIONS No.ooO4L l/2500 60 *00(. Saud and Hard Clay --- Plastic Clay & --. +For intemxdiite ratios of L/H.. mm mm (9) 75 75 (7) (Y) +033L l/300 *0021L i/500 (4) (5) (6) 50 +033L l/300 :0015L 11666 75 (7) (8) *0039L l/300 *0015L l/666 mm ( 12 ) log loo (Y) 9033L M2L (“1’3 l/3& l/500 . * v-7 \ mm (2) (3) (1) 50 i) For steel structure 50 ii) For reinforced concrete Wuctums iii) For multistoreyed buildings a) RC or steelframed 60 buildings with panel walls bj IGr~oad bearing 1) L/H = 2+ 60 mm mm mm mm. the values can be+erpolated. H denotes the height of wall from foundation footing. L denotes the length of deflected part of wall/raft or centreAo-antre distsnce between columns.-I Sand and Hard Clay Plastic Clay .3. y P I CI # Not likely to be encountered 60 . .7+ 75 +015L l/666 100 *0025L l/400 125 6025L l/40 50 go15L l/666 iv) For water towers and silos Nom -The values given in the table may be taken only as a guide and the permissible total settlement/different settlement and tilt ( angular distortion j in each case should be decided ss per rquirements of the designer. likely to interfere with the work shall be removed.If the site of a structure is such that surface water shall drain towards it.The datum lines parallel to and at the known fixed distance from the centre lines of the external walls also be permanently worked on the corresponding rows of pillars to pillars to serve as checks on the accuracy of the work as it proceeds. diagonals shall be checked to ensure accuracy.IS: 1904 . 20. In other cases ihese shall be set out by measurement of sides.1 The protection OF EXCAVATION of excavation during 20 construction of timbering and . It is recommended that safe bearing capacity shall be calculated on the basis of soil test data and in the absence of such data for preliminary design. burrowing by animals.4 Setting Out -. 19.Any obstacles. uprooted trees. The tops of these pillars shall be at the same level and preferably at the plinth or floor level.1986 relevant Indian Standards. Holes left by digging. including the stump of trees. PRELIMINARY WORK FOR CONSTRUCTION 19. In case of sloping terrain. parallel to and at a suitable distance beyond the periphery of the building.3 Drainage . Generally the site shall be levelled before the layout of foundations are set out. 19. shall be taken to protect the already alternatively. Angle!: should be set out with theodolites in the case of important and mlricate structures where the length of area exceeds 16 m. 19. sufficient precautions constructed foundations during subsequent work. etc.1 The construction of access roads. such as those due to removal of old foundation. the local values may serve as guidelines. Jn rectangular or square setting out.2 Clearance of Site .5 The layout of foundations shall be set out with steel tapes. 19. PROTECTION 20.lid ?o divert the water away from t!le site. The setting out of walls shall be facilitated by permanent row of pillars. main sewers and drains should preferably be completed before commencing the work of foundations. 19. care shall be taken to ensure that the dimensions on plans are set out correctly in one or more horizontal planes. The centre lines of the cross walls shall be extended to and permanently erected on the plastered tops of the corresponding sets of pillars. The pillars shall be located at junctions of cross walls with the penphera! line of pillars. The pillars shall be of sizes not !ess Phan 25 cm wide and shall be bedded sufficiently deep into ground so that they are not disturbed. land may be dressed or drains l. shall be back-filled with soil and well compacted. The bed shall be wetted and compacted by heavy rammers to an even surface.4 The refilling of the excavation shall he done with care so as not to disturb the constructed foundation.3 Excavation in clay or o. where necessary. *Specificationfor safety code for excavation work. shall be done in accordance with IS : 3764-1966*. the bottom of the excavation shall be cleared of all loose soil and rubbish and shall be levelled.Is:1904-1986 dewatering operations. wherever possible.ther soils that are liable to be effected by exposure to atmosphere shall. 21 . the last excavation of about 10 cm shall be removed only before concreting. 20. compaction. be concreted as soon as they are dug. 20. and shall be compacted in layers not exceeding 15 cm thick with sprinkling of minimum quantity of water necessary for proper. or in order to obtain a dry hard boftom. where necessary. 20.2 After excavation. Alternatively the bottom of the excavation shall be protected immediately by 8 cm thick layer of cement concrete not leaner than mix 1 : 5 : 10 over which shall come the foundation concrete. Ministry SHRI K. M. AGARWAL LT-COL C. Bombay SHRI D. HARJDAS SHRJ A. New Delhi VII Cent. L. TELANG ( Alternate ) In personal capacity ( E-104A SHRJ S. GHOSAL ( Alternate ) Engineers India Ltd. New Delhi SHRIMIYENGAR DR R. BDC 43 : 6 Representing Calcutta Port Trust. Bombay SHRI G. RAMKRJSHNAN SHRJ A. Calcutta Ministry of Communication Engineer-in-Chief’s Branch. Roorkee Panel for Revision Convener SHRJ S. S. GUHA Members Foundation Subcommittee. BOSE SHRI K. Madras Central Public Works Department. R. Bombay ) Construction Corporation Cement Corporation of India. SRIVASTAVA SHRI SWAMI SARAN Engineering Madras Simla House. GHOSH ( Alternote ) SHRJ S. GUHA of IS : 1904. K. ASSUDANI MAI T. DATTA ( Alrernate ) DIRECTOR DIVISIONALENGINEER SOILS) i ( Abernafe ) EXECIJT~VFZ ENGINEER( DESIGNS) V EXECUTIVE ENGINEER DESIGNS) ( ( Alternate ) SHRI A. BHANDARJ ( Afternuts ) Ministry of Railways JOINTDIRECTOR ( GE ) DEPUTY DIRECTOR( GE III ) ( AlterRare ) Cemindia Co Ltd. K.P. MUKHERJEE SKRJ P. K. KETKAR SHR~ R. Members SHRI S. New Delhi University of Roorkee. R. C. K. A~ARWAL 22 . G. DATAR ( Alternate ) SHRJ 0. J. Calcutta Foundations Construction Calcutta Ministry .CHAKRABARTI SHRJP. B. L. BDC 43 : 6/Pl Calcutta Port Trust. SONEJA Altermzfe ) ( Gammon India Ltd.IS : 1904. GHOSH of Defence Ministry of Transport ( Roads Wing ) Highways and Rural Works Department.of Communication Pile ( I ) Pvt Ltd. Ltd. Nepean Sea Road. SHRI M. G.1986 ( Conf huedfrom page 2 ) Miscellaneous Convener SiiRI S.~r~~~lding Research Institute ( CSIR ).K. N. HYDERABAD 500001 R14 Yudhlrter Marg.BUREAU OF INDIAN STA_NDARDS Manrk Bhavan. Scheme VII M. G. P. Marol. C Scheme. PATNA 800013 Hantex Bldg ( 2nd Floor ). Squaw 330001 600113 ‘Pumhpak’ Nurmohamed AHMADABAD ‘F’ Block Unlty Bldg. Sector 35-C. Bhadbhada BHOPAL 462003 Road. 0 Bahatir Tolophonos ShahZatar Mar& t 331 01 31. f. strot. Campus. Ward No. NAGPUR 440010 lnstltutlon of Engineers PUNE411006 %~OS ( lndla ) Bullding. 23 10 33 6 tI8 32 21 68 76 8 28 06 7 66 37 I Manakalaya.331 13 76 NEW DELHI 110002 Tolograme I Manaksanrthr ( Common to all ofhcor ) R~gion8l *Woetorn fEaetorn Southern Northern 8rwrch Ol/lcor I ( East ). Rly Statlon Road. 2 51 71 8 24 36 OftIc@ In Bombay Ir at N~volty Chambora. Khrnpur. CALCUTTA 700054 I C I. I. Bharampeth Extension. 29. TRIVANORUM 695001 /nrgact/on Off/co ( Wlth Sale Point 1 I Pushpanjali 205-A West Hlgh Court Road. KANPUR 2080(X1 Patllputra lndustrlal Estate. 3283. Grant bay 400007 cb ato8 OfRco In Calcutta Ie at I Chowrlnghro Approach. Lewis Road.. JAIPUR 302006 lt7/418 B Sarvodaya Nagar. T. V. 89 55 s5 575555 prfnc. T. Plot No. Nagar. . 1. EO MIDC. Andherl BOMBAY 400093 I l/14 C. I. BHUBANESHWAR 751009 6315. Naraslmharaja BANGALORE 660002 Gangotrl Complex. P 0. MADRAS I SC0 445-446. GUWAHATI 781003 !I-866C L. CHANOIGARH 160036 Otflc#s ) Shaikh Maw. 1332 Shlvajl Nagar. Calcutta 700075 lo Road. 6 32 92 96 36 24 99 41 24 42 2 13 43 3 16 41 2 63 48 1 2 6348 22 43 06 667 16 6 36 27 -. ToIt @on. Road. Maniktola. Gupta Marg. R. Barua Road 5th Byelane. Documents Similar To Is 1904 Code of Practice for Design and Construction of FounSkip carouselcarousel previouscarousel next6403Transformer Foundation DesignIS 6403Strap Footing sample.pdfCircular Slab8009_1IS:2386_2IRC SP 89-2010is.1904.1986.pdfIs 1077 Common Burnt Clay Building BricksSP24SKEW BRIDGES-N.RAJAGOPALAN.pdfWell FoundationSri. 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